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If you are using the Land file, you can go back to ArcCatalog and find CodeDescriptions.gdb\LandUseCode_CodeDescriptions to figure out what the codes mean (look at drag the file using Preview tab in ArcCatalog LandUseCode_CodeDescriptions file into your map and then open the table).
As the file will be very large, be sure to clip it. Then, you can join tables.
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